The present disclosure relates to an encapsulation, barrier or protective layer suitable for the protection of organic electronic devices. In particular, the present disclosure relates to the use of a lac-based material to form an encapsulation, barrier or protective layer for electronic devices such as, for example, thin film transistors or organic light emitting diodes. The term “encapsulation layer”, “barrier layer”, and “protective layer” in embodiments herein are used to imply essentially the same entity or component which insulates the electronic device from environmental constituents which may otherwise adversely affect the device's structural integrity, functional performance, or operational life time.
An encapsulation layer for thin film transistors (TFTs) is used herein to illustrate the concept of the present disclosure for the protection of organic electronic devices. It is understood that the present disclosure can be extended to other devices such as organic light emitting diodes.
Thin film transistors are important components of electronic circuits. A TFT comprises of a supporting substrate, three electrically conductive electrodes (gate, source and drain electrodes), a semiconductive layer and a dielectric layer. Various TFT configurations are possible to enable proper functioning of TFTs in various electronic applications. The semiconductor is electrically insulating when the transistor is in its switched-off state, when no bias voltage is applied to the gate electrode. When a bias voltage is applied to the gate electrode, the transistor is switched on, an electric current flows between the source and the drain electrodes through the semiconductor layer. At a given source-drain electric field, the current flowing between the source-drain electrodes can be modulated by the bias voltage applied to the gate electrode
Organic electronic devices such as TFTs can be damaged by environmental elements such as light, water, and oxygen. To protect against the ingress of environmental elements, an organic electronic device is often encapsulated. The encapsulation layer may include an inorganic material or an organic polymer material. For example, inorganic material-based TFTs, such as amorphous silicon TFTs, may be passivated with a vacuum deposited inorganic oxide layer (e.g., silicon oxides). Organic electronic devices may be encapsulated with polymers such as polymethyl methacrylate, polyethylene, polyethyleneterephthalate, and the like. The encapsulation layer may also include protective materials such as antioxidants, desiccants, and mixtures of thereof. Such protective materials have a finite capacity to function for their intended purposes. Further, the encapsulation layer may be a multilayer structure. The use of these protective materials or structures, however, may involve complex formulations and/or processing, which can lead to an increase in time and cost to produce an electronic device.
Therefore there is a need to provide an encapsulation layer for an electronic device such as a TFT to adequately protect it from environmental elements that may adversely affect the device's structural stability and electronic performance. There is also a need for an encapsulation layer that is easily processed and formed over an electronic device. The need also exists for an encapsulation layer for an electronic device that adequately protects the device from environmental elements without the need for additional components such as desiccants, antioxidants, and mixtures of thereof.